armsrc/epa.c

   1 //-----------------------------------------------------------------------------
   2 // Frederik Möllers - August 2012
   3 //
   4 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
   5 // at your option, any later version. See the LICENSE.txt file for the text of
   6 // the license.
   7 //-----------------------------------------------------------------------------
   8 // Routines to support the German eletronic "Personalausweis" (ID card)
   9 // Note that the functions which do not implement USB commands do NOT initialize
  10 // the card (with iso14443a_select_card etc.). If You want to use these
  11 // functions, You need to do the setup before calling them!
  12 //-----------------------------------------------------------------------------
  13
  14 #include "iso14443a.h"
  15 #include "epa.h"
  16 #include "cmd.h"
  17
  18 // Protocol and Parameter Selection Request
  19 // use regular (1x) speed in both directions
  20 // CRC is already included
  21 static const uint8_t pps[] = {0xD0, 0x11, 0x00, 0x52, 0xA6};
  22
  23 // APDUs for communication with German Identification Card
  24
  25 // General Authenticate (request encrypted nonce) WITHOUT the Le at the end
  26 static const uint8_t apdu_general_authenticate_pace_get_nonce[] = {
  27         0x10, // CLA
  28         0x86, // INS
  29         0x00, // P1
  30         0x00, // P2
  31         0x02, // Lc
  32         0x7C, // Type: Dynamic Authentication Data
  33         0x00, // Length: 0 bytes
  34 };
  35
  36 // MSE: Set AT (only CLA, INS, P1 and P2)
  37 static const uint8_t apdu_mse_set_at_start[] = {
  38         0x00, // CLA
  39         0x22, // INS
  40         0xC1, // P1
  41         0xA4, // P2
  42 };
  43
  44 // SELECT BINARY with the ID for EF.CardAccess
  45 static const uint8_t apdu_select_binary_cardaccess[] = {
  46         0x00, // CLA
  47         0xA4, // INS
  48         0x02, // P1
  49         0x0C, // P2
  50         0x02, // Lc
  51         0x01, // ID
  52         0x1C  // ID
  53 };
  54
  55 // READ BINARY
  56 static const uint8_t apdu_read_binary[] = {
  57         0x00, // CLA
  58         0xB0, // INS
  59         0x00, // P1
  60         0x00, // P2
  61         0x38  // Le
  62 };
  63
  64
  65 // the leading bytes of a PACE OID
  66 static const uint8_t oid_pace_start[] = {
  67     0x04, // itu-t, identified-organization
  68     0x00, // etsi
  69     0x7F, // reserved
  70     0x00, // etsi-identified-organization
  71     0x07, // bsi-de
  72     0x02, // protocols
  73     0x02, // smartcard
  74     0x04 // id-PACE
  75 };
  76
  77 //-----------------------------------------------------------------------------
  78 // Closes the communication channel and turns off the field
  79 //-----------------------------------------------------------------------------
  80 void EPA_Finish()
  81 {
  82         FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
  83         LEDsoff();
  84 }
  85
  86 //-----------------------------------------------------------------------------
  87 // Parses DER encoded data, e.g. from EF.CardAccess and fills out the given
  88 // structs. If a pointer is 0, it is ignored.
  89 // The function returns 0 on success and if an error occured, it returns the
  90 // offset where it occured.
  91 //
  92 // TODO: This function can access memory outside of the given data if the DER
  93 //       encoding is broken
  94 // TODO: Support skipping elements with a length > 0x7F
  95 // TODO: Support OIDs with a length > 7F
  96 // TODO: Support elements with long tags (tag is longer than 1 byte)
  97 // TODO: Support proprietary PACE domain parameters
  98 //-----------------------------------------------------------------------------
  99 size_t EPA_Parse_CardAccess(uint8_t *data,
 100                             size_t length,
 101                             pace_version_info_t *pace_info)
 102 {
 103         size_t index = 0;
 104
 105         while (index <= length - 2) {
 106                 // determine type of element
 107                 // SET or SEQUENCE
 108                 if (data[index] == 0x31 || data[index] == 0x30) {
 109                         // enter the set (skip tag + length)
 110                         index += 2;
 111                         // check for extended length
 112                         if ((data[index - 1] & 0x80) != 0) {
 113                                 index += (data[index-1] & 0x7F);
 114                         }
 115                 }
 116                 // OID
 117                 else if (data[index] == 0x06) {
 118                         // is this a PACE OID?
 119                         if (data[index + 1] == 0x0A // length matches
 120                             && memcmp(data + index + 2,
 121                                       oid_pace_start,
 122                                       sizeof(oid_pace_start)) == 0 // content matches
 123                             && pace_info != NULL)
 124                         {
 125                                 // first, clear the pace_info struct
 126                                 memset(pace_info, 0, sizeof(pace_version_info_t));
 127                                 memcpy(pace_info->oid, data + index + 2, sizeof(pace_info->oid));
 128                                 // a PACE OID is followed by the version
 129                                 index += data[index + 1] + 2;
 130                                 if (data[index] == 02 && data[index + 1] == 01) {
 131                                         pace_info->version = data[index + 2];
 132                                         index += 3;
 133                                 }
 134                                 else {
 135                                         return index;
 136                                 }
 137                                 // after that there might(!) be the parameter ID
 138                                 if (data[index] == 02 && data[index + 1] == 01) {
 139                                         pace_info->parameter_id = data[index + 2];
 140                                         index += 3;
 141                                 }
 142                         }
 143                         else {
 144                                 // skip this OID
 145                                 index += 2 + data[index + 1];
 146                         }
 147                 }
 148                 // if the length is 0, something is wrong
 149                 // TODO: This needs to be extended to support long tags
 150                 else if (data[index + 1] == 0) {
 151                         return index;
 152                 }
 153                 else {
 154                         // skip this part
 155                         // TODO: This needs to be extended to support long tags
 156                         // TODO: This needs to be extended to support unknown elements with
 157                         //       a size > 0x7F
 158                         index += 2 + data[index + 1];
 159                 }
 160         }
 161
 162         // TODO: We should check whether we reached the end in error, but for that
 163         //       we need a better parser (e.g. with states like IN_SET or IN_PACE_INFO)
 164         return 0;
 165 }
 166
 167 //-----------------------------------------------------------------------------
 168 // Read the file EF.CardAccess and save it into a buffer (at most max_length bytes)
 169 // Returns -1 on failure or the length of the data on success
 170 // TODO: for the moment this sends only 1 APDU regardless of the requested length
 171 //-----------------------------------------------------------------------------
 172 int EPA_Read_CardAccess(uint8_t *buffer, size_t max_length)
 173 {
 174         // the response APDU of the card
 175         // since the card doesn't always care for the expected length we send it,
 176         // we reserve 262 bytes here just to be safe (256-byte APDU + SW + ISO frame)
 177         uint8_t response_apdu[262];
 178         int rapdu_length = 0;
 179
 180         // select the file EF.CardAccess
 181         rapdu_length = iso14_apdu((uint8_t *)apdu_select_binary_cardaccess,
 182                                   sizeof(apdu_select_binary_cardaccess),
 183                                   response_apdu);
 184         if (rapdu_length != 6
 185             || response_apdu[rapdu_length - 4] != 0x90
 186             || response_apdu[rapdu_length - 3] != 0x00)
 187         {
 188                 Dbprintf("epa - no select cardaccess");
 189                 return -1;
 190         }
 191
 192         // read the file
 193         rapdu_length = iso14_apdu((uint8_t *)apdu_read_binary,
 194                                   sizeof(apdu_read_binary),
 195                                   response_apdu);
 196         if (rapdu_length <= 6
 197             || response_apdu[rapdu_length - 4] != 0x90
 198             || response_apdu[rapdu_length - 3] != 0x00)
 199         {
 200                 Dbprintf("epa - no read cardaccess");
 201                 return -1;
 202         }
 203
 204         // copy the content into the buffer
 205         // length of data available: apdu_length - 4 (ISO frame) - 2 (SW)
 206         size_t to_copy = rapdu_length - 6;
 207         to_copy = to_copy < max_length ? to_copy : max_length;
 208         memcpy(buffer, response_apdu+2, to_copy);
 209         return to_copy;
 210 }
 211
 212 //-----------------------------------------------------------------------------
 213 // Abort helper function for EPA_PACE_Collect_Nonce
 214 // sets relevant data in ack, sends the response
 215 //-----------------------------------------------------------------------------
 216 static void EPA_PACE_Collect_Nonce_Abort(uint8_t step, int func_return)
 217 {
 218 //      // step in which the failure occured
 219 //      ack->arg[0] = step;
 220 //      // last return code
 221 //      ack->arg[1] = func_return;
 222
 223         // power down the field
 224         EPA_Finish();
 225
 226         // send the USB packet
 227   cmd_send(CMD_ACK,step,func_return,0,0,0);
 228 }
 229
 230 //-----------------------------------------------------------------------------
 231 // Acquire one encrypted PACE nonce
 232 //-----------------------------------------------------------------------------
 233 void EPA_PACE_Collect_Nonce(UsbCommand *c)
 234 {
 235         /*
 236          * ack layout:
 237          *      arg:
 238          *              1. element
 239          *           step where the error occured or 0 if no error occured
 240      *       2. element
 241      *           return code of the last executed function
 242          *      d:
 243          *              Encrypted nonce
 244          */
 245
 246         // return value of a function
 247         int func_return = 0;
 248
 249 //      // initialize ack with 0s
 250 //      memset(ack->arg, 0, 12);
 251 //      memset(ack->d.asBytes, 0, 48);
 252
 253         // set up communication
 254         func_return = EPA_Setup();
 255         if (func_return != 0) {
 256                 EPA_PACE_Collect_Nonce_Abort(1, func_return);
 257                 return;
 258         }
 259
 260         // increase the timeout (at least some cards really do need this!)
 261         iso14a_set_timeout(0x0002FFFF);
 262
 263         // read the CardAccess file
 264         // this array will hold the CardAccess file
 265         uint8_t card_access[256] = {0};
 266         int card_access_length = EPA_Read_CardAccess(card_access, 256);
 267         // the response has to be at least this big to hold the OID
 268         if (card_access_length < 18) {
 269                 EPA_PACE_Collect_Nonce_Abort(2, card_access_length);
 270                 return;
 271         }
 272
 273         // this will hold the PACE info of the card
 274         pace_version_info_t pace_version_info;
 275         // search for the PACE OID
 276         func_return = EPA_Parse_CardAccess(card_access,
 277                                            card_access_length,
 278                                            &pace_version_info);
 279         if (func_return != 0 || pace_version_info.version == 0) {
 280                 EPA_PACE_Collect_Nonce_Abort(3, func_return);
 281                 return;
 282         }
 283
 284         // initiate the PACE protocol
 285         // use the CAN for the password since that doesn't change
 286         func_return = EPA_PACE_MSE_Set_AT(pace_version_info, 2);
 287
 288         // now get the nonce
 289         uint8_t nonce[256] = {0};
 290         uint8_t requested_size = (uint8_t)c->arg[0];
 291         func_return = EPA_PACE_Get_Nonce(requested_size, nonce);
 292         // check if the command succeeded
 293         if (func_return < 0)
 294         {
 295                 EPA_PACE_Collect_Nonce_Abort(4, func_return);
 296                 return;
 297         }
 298
 299   // all done, return
 300         EPA_Finish();
 301
 302         // save received information
 303 //      ack->arg[1] = func_return;
 304 //      memcpy(ack->d.asBytes, nonce, func_return);
 305   cmd_send(CMD_ACK,0,func_return,0,nonce,func_return);
 306 }
 307
 308 //-----------------------------------------------------------------------------
 309 // Performs the "Get Nonce" step of the PACE protocol and saves the returned
 310 // nonce. The caller is responsible for allocating enough memory to store the
 311 // nonce. Note that the returned size might be less or than or greater than the
 312 // requested size!
 313 // Returns the actual size of the nonce on success or a less-than-zero error
 314 // code on failure.
 315 //-----------------------------------------------------------------------------
 316 int EPA_PACE_Get_Nonce(uint8_t requested_length, uint8_t *nonce)
 317 {
 318         // build the APDU
 319         uint8_t apdu[sizeof(apdu_general_authenticate_pace_get_nonce) + 1];
 320         // copy the constant part
 321         memcpy(apdu,
 322                apdu_general_authenticate_pace_get_nonce,
 323                sizeof(apdu_general_authenticate_pace_get_nonce));
 324         // append Le (requested length + 2 due to tag/length taking 2 bytes) in RAPDU
 325         apdu[sizeof(apdu_general_authenticate_pace_get_nonce)] = requested_length + 4;
 326
 327         // send it
 328         uint8_t response_apdu[262];
 329         int send_return = iso14_apdu(apdu,
 330                                      sizeof(apdu),
 331                                      response_apdu);
 332         // check if the command succeeded
 333         if (send_return < 6
 334                 || response_apdu[send_return - 4] != 0x90
 335                 || response_apdu[send_return - 3] != 0x00)
 336         {
 337                 return -1;
 338         }
 339
 340         // if there is no nonce in the RAPDU, return here
 341         if (send_return < 10)
 342         {
 343                 // no error
 344                 return 0;
 345         }
 346         // get the actual length of the nonce
 347         uint8_t nonce_length = response_apdu[5];
 348         if (nonce_length > send_return - 10)
 349         {
 350                 nonce_length = send_return - 10;
 351         }
 352         // copy the nonce
 353         memcpy(nonce, response_apdu + 6, nonce_length);
 354
 355         return nonce_length;
 356 }
 357
 358 //-----------------------------------------------------------------------------
 359 // Initializes the PACE protocol by performing the "MSE: Set AT" step
 360 // Returns 0 on success or a non-zero error code on failure
 361 //-----------------------------------------------------------------------------
 362 int EPA_PACE_MSE_Set_AT(pace_version_info_t pace_version_info, uint8_t password)
 363 {
 364         // create the MSE: Set AT APDU
 365         uint8_t apdu[23];
 366         // the minimum length (will be increased as more data is added)
 367         size_t apdu_length = 20;
 368         // copy the constant part
 369         memcpy(apdu,
 370                apdu_mse_set_at_start,
 371                sizeof(apdu_mse_set_at_start));
 372         // type: OID
 373         apdu[5] = 0x80;
 374         // length of the OID
 375         apdu[6] = sizeof(pace_version_info.oid);
 376         // copy the OID
 377         memcpy(apdu + 7,
 378                pace_version_info.oid,
 379                sizeof(pace_version_info.oid));
 380         // type: password
 381         apdu[17] = 0x83;
 382         // length: 1
 383         apdu[18] = 1;
 384         // password
 385         apdu[19] = password;
 386         // if standardized domain parameters are used, copy the ID
 387         if (pace_version_info.parameter_id != 0) {
 388                 apdu_length += 3;
 389                 // type: domain parameter
 390                 apdu[20] = 0x84;
 391                 // length: 1
 392                 apdu[21] = 1;
 393                 // copy the parameter ID
 394                 apdu[22] = pace_version_info.parameter_id;
 395         }
 396         // now set Lc to the actual length
 397         apdu[4] = apdu_length - 5;
 398         // send it
 399         uint8_t response_apdu[6];
 400         int send_return = iso14_apdu(apdu,
 401                                      apdu_length,
 402                                      response_apdu);
 403         // check if the command succeeded
 404         if (send_return != 6
 405                 || response_apdu[send_return - 4] != 0x90
 406                 || response_apdu[send_return - 3] != 0x00)
 407         {
 408                 return 1;
 409         }
 410         return 0;
 411 }
 412
 413 //-----------------------------------------------------------------------------
 414 // Set up a communication channel (Card Select, PPS)
 415 // Returns 0 on success or a non-zero error code on failure
 416 //-----------------------------------------------------------------------------
 417 int EPA_Setup()
 418 {
 419
 420         int return_code = 0;
 421         uint8_t uid[10];
 422         uint8_t pps_response[3];
 423         uint8_t pps_response_par[1];
 424         iso14a_card_select_t card_select_info;
 425
 426         // power up the field
 427         iso14443a_setup(FPGA_HF_ISO14443A_READER_MOD);
 428
 429         iso14a_set_timeout(10500);
 430
 431         // select the card
 432         return_code = iso14443a_select_card(uid, &card_select_info, NULL);
 433         if (return_code != 1) {
 434                 Dbprintf("Epa: Can't select card");
 435                 return 1;
 436         }
 437
 438         // send the PPS request
 439         ReaderTransmit((uint8_t *)pps, sizeof(pps), NULL);
 440         return_code = ReaderReceive(pps_response, pps_response_par);
 441         if (return_code != 3 || pps_response[0] != 0xD0) {
 442                 return return_code == 0 ? 2 : return_code;
 443         }
 444
 445         return 0;
 446 }